12大地测量学概念.doc

1、Unit 12 Geodesy Concepts（大地测量学概念）As we know, surveying is divided into two major categories: geodetic surveying and planesurveying.（我们知道，测量分为两个主要范畴【category 种类、范畴】：大地测量和平面测量）Geodetic surveying takes into account the true shape of the earth whereas plane surveyingtreats the earth as a flat surface（.大

2、地测量要考虑【take into account考虑】地球的真实形状，而【 whereas然而、可是】平面测量把地球视为【treat】一个平面）The subject of this text aims at the study of the size and shape of the earth which refers toGeodesy（.这篇文章的主题【subject】针对【 aim at】的就是涉及【 refer to】大地测量学的地球的大小和形状的研究）The expression “ thesize and shape ofthe earth”has various meanin

3、gs ingeodesyaccording to the way it is used and the precision with which the earthbe defined（.依照【 according to】定义地球大小和形状所使用的方法和精度， “地球的大小和形状”的表达在大地测量学中有各种各样的【various】含义）The actual topographic surface is most apparent with its variety of landforms and waterareas（.实际的地表【 topographic 地形的、地形学的surface 表面

4、 这里直接译为地表】大多表现为地形【 landform】和水域的多样性【 variety】）【is most apparent with 副词短语做表语】This is, in fact, the surface on which actual earth measurements are made.（事实上【 infact】，事实上，这就是所做的地球实际表面测量。）It is not suitable, however, for exact mathematical computations because the formulas which would be required to ta

5、ke the irregularities into account would necessitate a prohibitive amount of computations（.然而，对于精确的【exact】数学计算这并不合适，因为需要考虑到【 take into account】不规则【 irregularity 】的公式【 formula】将需要【 necessitate需要、被需要】大量的【 prohibitive 非常高的、受抑止的、禁止的】计算）The concept of geodesy should be mentioned first（.首先应该说一下【 mention 提

6、及】大地测量学的概念）From the Concise Oxford Dictionary: geodesy. n. The branch of mathematics dealing withthe figures and areas of the earth or large portions of it（.简明【 Concise 简明的】牛津词典：大地测量学 n.名词 . 数学的一个分支， 用来处理地球或其一大部分 【portion 一部分】的形状和区域）Encyclopedia of Science and Technology, 2001 edition, Academic Pres

7、s, 2000: Geodesy isa science, the oldest earth (geo-) science, in fact.（科学与技术百科全书【Encyclopedia百科全书】，2001 版，学术出版社【Academic Press】，2000：大地测量学是一门科学，事实上，是最古老的地球科学）It was born of fear and curiosity, driven by a to predict natural happenings and calls for theunderstanding of these happenings（.受预知【 predict

8、】自然事件【现象】和要求理解这些事件【现象】的愿望所驱动，由恐惧和好奇而生。）The classical definition, according to one of the“ fathers of geodesy”the science of measuring and portraying the earth s surface”（Helmert,经典 188【classical 经典的、古典的】定义， 依照“大地测量学之父” 的其中一位的说法：“大地测量学是测量和描绘【portray】地球表面的科学”Helmert, 1880, p.3）【Helmert德国人赫尔默特（F.R.Helm

9、ert，18431917）首创海上重力测定】Nowadays, we understand the scope of geodesy to be somewhat wider（.如今，我们理解大地测量学的范围【 scope范围】就有些【 somewhat有些】宽了）It is captured by the following definition Vanicek and Krakiwsky, 1986, p. 45:is the discipline that deals with the measurement and representation of the earth, includ

10、ingits gravity field, in a three-dimensional time varying space. （”从下列定义就可以得知【capture 俘获、获得，这里指可由下面的定义所了解】Vanicek and Krakiwsky, 1986,p. 45：“大地测量学是涉及【 deal with 】，在一个三维的时空中，测量和描述包括重力场在内的地球的一门学科【 discipline 学科】）Accordingto the classical definitionofHelmert,geodesy isthe“ scienceofthemeasurement and m

11、apping of the earths surface（依照赫”尔.默特的经典定义，大地测量学是“测量和绘制地球表面的科学” ）This definition has to this day retained its validity; it includes the determination of theearth s external gravity field, as well as the surface of the ocean（floor这个.定义时至今日【 to this day 至今】还保留着【 retain 保留】它的有效性【 validity 有效性、正确性】；它包括地

12、球的外部【 external 外部、外部的】重力场、也包括了海洋底部的表面的测定【 determination 这里翻译成测定】。）With this definition, which as to be extended to include temporal variations of the earth and its gravity field, geodesy may be included in the geosciences, and also in engineeringsciences, e.g., National Academy of Sciences (1978)（.依

13、照这个定义关于【as to】被扩展包括时间变量【 temporal 时间的； variation 变量】的地球和它的重力场，大地测量学可以被包括进地球科学、也可以被包括进工程学，例如【e.g.注意读音 i:dgi 】，国家科学院（ 1978）So, we velearned that Geodesy is the discipline that deals with the measurement and representation of the earth, its gravity field and geodynamic phenomena (polar motion, earth ti

14、des, and crustal motion) in three-dimensional time varying space（.这样【 so】，我们已经知道了大地测量学是关于在三维时空中测量和表述地球本身、它的重力场和地球动力学【 geodynamic】现象（极移【 motion 移动】，固体潮，和地壳【 crustal】运动）的学科【 discipline】）Geodesy is primarily concerned with positioning and the gravity field and geometricalaspects of their temporal varia

15、tions（.大地测量学主要涉及它们的时间变量【temporal 时间的； variation 变量】的位置、重力场和几何外表）Triggered by the development of space exploration, geodesy turned in collaboration with other sciences toward the determination of the surfaces of other celestial bodies (moon, other planets).（由于空间探索的发展的触发【 Trigger】，大地测量学转而与其它科学合作【in co

16、llaboration with 与 合作】，来【toward 为了、向】确定其它天体【celestialbody】（月球、其它行星）的表面）The corresponding disciplines are called selenodesy and planetary geodesy（.其相应的学科被称为月面测量学【 selenodesy】和行星大地测量学【 planetary geodesy】）Geodesy may be divided into three basic subdisciplines: geometric geodesy, physicalgeodesy, and sp

17、ace geodesy（.大地测量学可以分成三个基本分支：几何大地测量学、物理大地测量学、和空间大地测量学）Geometric geodesy (also called astro-geodesy) concerns with determination of the sizeand shape of the earth as well as the position on the earth surface（.几何大地测量学（也称为天文大地测量学【astro-geodesy】）涉及确定地球大小和形状，还有地球表面上的位置的确定。）For the purpose of deducing the

18、 size and shape of the earth and the precise location ofspecific positions on the earth s surface, geometric geodesy considers the geoid ththe use of astrogeodetic methods（.为了【 For the purpose of】推出【 deduce】地球的大小和形状，还有地球表面上的明确 【specific 明确的】位置的精确定位【 location 位置、点位 n.】，几何大地测量学考虑的是大地水准面，通过几何大地测量的方法）Th

19、is aspect of the science is involved with the basic principles of the establishment of the national geodetic networks which include both horizontal and vertical controls and strictly geometrical relationships measured in various ways: astronomic positioning, triangulation, trilateration, and travers

20、e are four traditional surveying techniques in general use for determining the exact positions of points on the earth surface（.该学科【thes science】的这个方面【 aspect】涉及建立国家大地网的基本原理【basic principle】，包括水平和高程控制，并以不同方式【 in various ways】严格测定几何关系：天文定位、三角测量、三边测量、导线测量是在确定地表点精确位置时通常的四种传统测量技术）In recent years, modern

21、technological developments have added several new methodsutilizing artificial earth satellites.（近年来，现代科技的发展增加了几种利用【utilize利用】人造地球卫星【 artificial 人造的】的新方法。）Other methods relevant to geodetic surveying are being developed（.其它相关的【relevant相关的】大地测量方法也得到发展）Physical geodesy utilizes measurements and charact

22、eristics of the earth ty field ass grav well as theories regarding this field to deduce the shape of the geoid and in combinationwith arc measurements, the earth（物理s大size地测.量学利用【utilize 利用】测量和地球重力场特征还有关于重力场的理论，来推出大地水准面的形状；与弧度测量【 arc measurement】相结合【 in combination with 与 结合】推出地球的大小）With sufficient i

23、nformation regarding the earth s gravity field, it is possible to dgeoidal undulations, gravimetric deflections, and the earth（利用涉及地sflattening球重.力场充分的【 sufficient 】信息【 regarding 涉及，介词 prep.】，就可以确定大地水准面波动【 undulations】、重力偏差【 gravimetric deflection】、和地球扁率）Space geodesy (Satellite geodesy) uses satell

24、ites for geodetic purposes which wereadvocated and published as early as 1956（.空间大地测量学 （卫星大地测量学） 把卫星用于大地测量的目的，早在【as early as 早在】 1956 年就被提出【 advocate】和发表【publish 发表、出版】了）With the constant growth of space technology, the development of electronic distance measuring devices, and the perfection of elec

25、tronic data processing equipment, satellites specifically equipped for geodetic purposes have been developed, launched, observed andthe data utilized. （随着空间技术的不断发展，电子测距仪的发展，和电子数据处理【 electronic data processing电子数据处理】装置的完善【perfection】，特为【specifically特别地】大地测量目的装备的卫星已经被发展、发射、观测和数据利用了【或译为：已经发展、发射、观测并其数据已

26、得到应用了】）Several observational systems, geodetic cameras, electronic ranging and Doppler SatelliteSurveys were developed and improved（.几种观测系统， 大地测量摄像机， 电子测距和多普勒卫星测量被发展和改善了）Some of the areas of new geodetic developments are: satellite laser ranging, lunar laser ranging, very long baseline interferometry, satellite radar altimetry, the Glob